Process of bronzing photographic plates.



UNITED STATES FFICE.

CARL PETER IIERMANN AI-IRLE, OF FRANKFORT-ON-Tl-IE-MAIN, GERMANY, ASSIGNOR TO METALLINE-PLATTEN-GESELLSCIIAFT M. B. II, OF FRANK- FORT-ON-THE-IWIAIN, GERMANY.

PROCESS OF BRONZ ING PHOTOGRAPHIC PLATES.

SPECIFICATION forming part of Letters Patent No. 694,227, dated February 25, 1902. Application filed May 17, 1901. Serial No- 60,'729. (No specimens.)

To aZZ whom 236 Hwy concern.-

Be it known that I, CARL PETER HERMANN AHRLE, asubject of the Kingof Prussia, German Emperor, residing at 32 Sandweg, Frankfort-on-the-Wlain, in the Kingdom of Prussia, Germany, haveinvented certain new and use f ul Improvements in Processes of Producing Bronze-OoatedPlates for Photographic Backgrounds, (for which I have filed an applica- [0 tion for Letters Patent in Germany January 31, 1901; in Great Britain March 25, 1901; in Austria March 11, 1901; in BelgiumApril 10, 1901; in Hungary March 2, 1901; in France April 22, 1901; in Italy April 22, 1901; in Russia March 8, 1901; in Denmark March 18, 1901; in Spain April 22, 1901; in Sweden March 18, 1901; in Luxemburg March 8, 1901; in Norway April 24, 1901, and in Switzerland April 22, 1901;) and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to a process for the production of bronze-coated plates to serve as a photographic background, which plates are produced in the manner herein set forth in the description and claims.

Hitherto many attempts have been made o to produce bronze coating for photographic backgrounds; but up to the present time none have proved satisfactory, one reason for this being that pliable materials-such as paper, textile fabrics, leather, or thelike-have been employed, to all of which materials serious objections exist. I have found it to be a prerequisite that the base must be of rigid material ;otherwise the coating will not be durable and homogeneous.

A bronze coating securedto paper or other fabric by means of gelatin having incorporated therein a metallic substance in the condition of a fine powder is not durable, since the flexibility of the paper or fabric inevitably causes cracks or flaws in the metallic layer. Moreover, a layer produced by bronze incorporated into gelatin, even if supported by a rigid body, is not durable for this purpose on account of the change in the temperature and the hygroscopic condition of the atmosphere. Even if such coatings are covered with collodion varnish they will not be satisfactory, as the objection of brittle ness still obtains even to a greater degree.

According to my process I take as the base some rigid material-such as wood, marble, metal, or the likeand add to it a suitable layer of varnish, preferably japan. This layer of varnish is then dried, smoothed, and polished. I then take a solution containing the following parts, by weight: sixteen of albumen, nine of honey, twenty-three of water. These materials are thoroughly mixed together'and carefully filtered. The plate covered with this varnish coating is then coated with this filtered solution, which penetrates into the fine pores of the varnish, thus efiecting a thorough combination between the solution and varnish. Before the solution has become perfectly dry the metallizing or bronzing should be effected. This is done as follows: The fine dry bronze-powder is applied with a fine brush to the slightly-moist surface of the plate, the application being continued until aunjform bronze layer is pro duced having a metallic luster and thoroughly combined with the coating formed on the layer of varnish by the solution. In this manner by the introduction of fine metallic particles into the solution and the varnish coating the varnish, the solution, and the bronze-powder form a thoroughly-homogeneous layer. This is then allowed to dry and alcohol is poured over it, which by its evaporation hardens the layer. The plate thus produced forms an admirable background for photographic purposes. The pictures formed thereon remain unaltered and are so perfect as to produce on the eye the impression of a plastic production.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is-

1. The process of producing bronze-coated plates for photographic purposes, which consists in applying to a rigid base a layer of varnish, a softening solution, and fine metallic powder in succession.

2. The process of producing bronze-coated men,honey and water, and then while still plates for photographic purposes, which con wet brushing a dry metallic powder over the sists in applying to a rigid base, varnish, a sosurface thereof, allowing it to 'd ry, and aplubion containing albumen, honey and water, plying alcohol thereto.

5 and metallic powder in succession.- In testimony whereof I have affixed my sig- 15 3. The process of producing bronze-coated nature in presence of two witnesses. plates for photographic purposes, which con- CARL PETER HER-MANN AIIRLE. sists in applying to a rigid plate a layer of l Witnesses:

varnish, smoothing and polishing the same, JEAN GRUND, IO then applying a solution composed of albu- CARL GRUND. 

